The present invention relates generally to a method and system for repairing a damaged hole. More particularly, the invention relates to a method and system for repairing an enlarged bolt hole on a composite nose cone of a gas turbine engine.
A removable nose cone is regularly attached to a hub in the center of the inlet of a gas turbine engine. The nose cone provides a smooth aerodynamic surface covering for the hub hardware and feeds air into the fan blades. In some engine designs the nose cone rotates with the fan blades.
The nose cone may be attached to the hub with a plurality of attachment bolts that pass through attachment holes on a flange of the nose cone that are aligned with corresponding holes on the hub. The flange includes alternating attachment holes and balance weight holes. The balance weight holes are used to balance the nose cone before installation of the nose cone to the hub by inserting bolts through the balance weight holes. The bolts for the attachment holes are inserted once the nose cone is aligned with the hub.
Due to the operating conditions inside a gas turbine engine, over time the attachment holes and the balance weight holes on the flange become enlarged. An enlarged hole allows the bolt to move around within the hole. Therefore, it may become necessary to restore the bolt holes so that the bolts are properly secured within the attachment holes and the balance weight holes.
One approach to repairing an enlarged hole includes filling the hole with chopped fiber-filled epoxy resin and then drilling out an area where the bolt is to be reinserted. However, this approach is inadequate in terms of its durability. Alternatively, replacing the entire nose cone is extremely expensive.
Therefore, there is a need for a cost-effective, yet durable, method of repairing an enlarged hole on various components.